Open Access

ARTICLE

Thermal Analysis of the Transcritical Organic Rankine Cycle Using R1234ze(E)/R134a Mixtures as Working Fluids

by Panpan Zhao, Dongdong Wang, Dao Zhou, Huan Zhang, Yun Sun

1 Hefei General Machinery Research Institute, Hefei, 230088, China
2 Anhui Vacree Technologies Co., Ltd., Hefei, 230088, China

* Corresponding Author: Panpan Zhao. Email:

Energy Engineering 2020, 117(4), 209-224. https://doi.org/10.32604/EE.2020.010567

Received 10 March 2020; Accepted 29 June 2020; Issue published 31 July 2020

Abstract

A R1234ze(E) based mixture was investigated as a promising environmental solution to enhance system performance of a transctitical organic Rankine cycle(TORC). The main purpose of this study is to research the thermodynamic properties of TORC system using R1234ze(E)/R134a mixtures with various mass fraction of R1234ze(E) when recovering engine exhaust heat. R1234ze(E) was selected due to its zero ozone depletion potential, relative lower global warming potential and it can remedy the thermodynamic properties of traditional working fluid R134a. Thermal analysis and optimization about expander inlet temperature and pressure of TORC, mass fraction of R134a in R134a/R1234ze(E) mixtures are carried out. According to the results, the designed parameters have great effect on the performance of TORC system, there is an optimal pressure to maximize the system performance, and the optimal pressure increases as temperature increases. However, when the expander inlet pressure is relatively lower, the TORC system working with pure R1234ze(E) has a best energy and exergy efficiency than working with other mixtures. When the expander inlet pressure is relatively higher, the TORC system working with pure R134a has a maximum energy and exergy effi- ciency than working with other mixtures. That is to say, the working conditions should be optimized and regulated in actual cycling system so as to recover more engine exhaust heat and obtain maximum expander output power, a best energy and exergy efficiency.

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